Mirror device

ABSTRACT

A mirror device includes: a mirror including a rotation shaft; a gear unit having gear teeth and coupled to the rotation shaft; a worm that meshes with the gear teeth; a holding member that supports the worm; a motor configured to rotationally drive the rotation shaft via the worm and the gear teeth; and a stopper mechanism ( 16 ) that has a rotating member disposed coaxially with the worm, and restricts a rotation range of the worm, in which the stopper mechanism includes: a first contact portion that is provided on the rotating member and comes in contact with the worm to receive force in the rotation direction from the worm; and a second contact portion that is provided on the rotating member and is locked by the holding member, the stopper mechanism being configured to allow the worm to rotate relative to the holding member by more than one rotation.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to and incorporates by referencethe entire contents of Japanese Patent Application No. 2019-198796 filedin Japan on Oct. 31, 2019.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a mirror device.

2. Description of the Related Art

There is a conventionally used mirror device.

Japanese Patent Application Laid-open No. 2000-137189 discloses ahead-up display device in which a drive motor swings a mirror through aworm gear and a worm wheel.

As a mechanism for defining the pivoting range of a mirror, provision ofa stopper mechanism for restricting the rotation range of the worm hasbeen examined. From the viewpoint of improving the degree of freedom incontrolling the rotational position of the mirror, it is advantageous toachieve a wide rotation range of the worm. For example, it is preferablethat the rotatable range of the worm exceeds one rotation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a mirror device capableof improving the degree of freedom in controlling the rotationalposition of the mirror.

In order to achieve the above mentioned object, a mirror deviceaccording to one aspect of the present invention includes a mirrorincluding a rotation shaft pivotably supported and a reflecting surfacethat reflects display light; a gear unit having gear teeth and coupledto the rotation shaft; a worm that meshes with the gear teeth; a holdingmember that rotatably supports the worm; a motor that is held by theholding member, connected to the worm, and configured to rotationallydrive the rotation shaft via the worm and the gear teeth; and a stoppermechanism that has a rotating member disposed coaxially with the worm,and restricts a rotation range of the worm, wherein the rotating memberis rotatable relative to the holding member and the worm individually,the stopper mechanism includes: a first contact portion that is providedon the rotating member and comes in contact with the worm to receiveforce in the rotation direction from the worm; and a second contactportion that is provided on the rotating member and is locked by theholding member, and the stopper mechanism is configured to allow theworm to rotate relative to the holding member by more than one rotation.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a schematic configuration of a vehicledisplay device according to an embodiment;

FIG. 2 is a perspective view of a mirror device according to anembodiment;

FIG. 3 is an exploded perspective view of a mirror device according toan embodiment;

FIG. 4 is a front view of a mirror device according to an embodiment;

FIG. 5 is a perspective view of holding member according to anembodiment;

FIG. 6 is a cross-sectional view of a holding member according to anembodiment;

FIG. 7 is a cross-sectional view of a holding member according to anembodiment;

FIG. 8 is a cross-sectional view illustrating a rotation shaft held by aholder of a holding member;

FIG. 9 is a perspective view of a bearing member according to anembodiment;

FIG. 10 is a cross-sectional view illustrating a rotation shaft held bya holder of a bearing member;

FIG. 11 is a front view of a worm according to an embodiment;

FIG. 12 is a view of a worm according to an embodiment as viewed in anaxial direction from the motor side;

FIG. 13 is a view of a worm according to an embodiment as viewed in anaxial direction from the rotating member side;

FIG. 14 is a perspective view of a rotating member according to anembodiment;

FIG. 15 is a front view of a rotating member according to an embodiment;

FIG. 16 is a perspective view of a main body of a coupling memberaccording to an embodiment;

FIG. 17 is a perspective view of a main body of a coupling memberaccording to an embodiment;

FIG. 18 is a side view of a main body of a coupling member according toan embodiment;

FIG. 19 is a front view of a gear unit of a coupling member according toan embodiment;

FIG. 20 is a view of a mirror device according to an embodiment asviewed along a first axis;

FIG. 21 is a perspective view of a mirror device according to anembodiment;

FIG. 22 is a cross-sectional view of a stopper mechanism according to anembodiment;

FIG. 23 is a cross-sectional view of a stopper mechanism according to anembodiment;

FIG. 24 is a cross-sectional view of a stopper mechanism according to anembodiment; and

FIG. 25 is a cross-sectional view of a stopper mechanism according to anembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a mirror device according to an embodiment of the presentinvention will be described in detail with reference to the drawings.Note that the present invention is not limited by this embodiment.Moreover, components in the following embodiment include those that areeasily conceivable for those skilled in the art or substantiallyidentical.

Embodiment

An embodiment will be described with reference to FIGS. 1 to 25. Thepresent embodiment relates to a mirror device. FIG. 1 is a schematicconfiguration diagram of a vehicle display device according to anembodiment. FIG. 2 is a perspective view of a mirror device according toan embodiment. FIG. 3 is an exploded perspective view of a mirror deviceaccording to an embodiment. FIG. 4 is a front view of a mirror accordingto an embodiment. FIG. 5 is a perspective view of a holding memberaccording to an embodiment. FIG. 6 is a cross-sectional view of aholding member according to an embodiment. FIG. 7 is a cross-sectionalview of a holding member according to an embodiment. FIG. 8 is across-sectional view of a rotation shaft held by a support portion of aholding member. FIG. 9 is a perspective view of a bearing memberaccording to an embodiment. FIG. 10 is a cross-sectional view of arotation shaft held by a support portion of a bearing member.

FIG. 11 is a front view of a worm according to an embodiment. FIG. 12 isa view of a worm according to an embodiment as viewed in an axialdirection from the motor side. FIG. 13 is a view of a worm according toan embodiment as viewed in an axial direction from the rotating memberside. FIG. 14 is a perspective view of a rotating member according to anembodiment. FIG. 15 is a front view of a rotating member according to anembodiment. FIG. 16 is a perspective view of a main body of a couplingmember according to an embodiment. FIG. 17 is a perspective view of themain body of a coupling member according to an embodiment. FIG. 18 is aside view of a main body of a coupling member according to anembodiment. FIG. 19 is a front view of a gear unit of a coupling memberaccording to an embodiment. FIG. 20 is a view of a mirror deviceaccording to an embodiment as viewed along a first axis.

FIG. 21 is a perspective view of a mirror device according to anembodiment. FIGS. 22 to 25 are cross-sectional views of a stoppermechanism according to an embodiment. FIG. 6 illustrates across-sectional view taken along line VI-VI in FIG. 7. FIGS. 7 and 8 arecross-sectional views taken along line VII-VII in FIG. 6. FIG. 10illustrates a cross section taken along line X-X in FIG. 9. FIGS. 22 to25 are cross-sectional views taken along line XXII-XXII in FIG. 20.

As illustrated in FIG. 1, a vehicle display device 10 according to anembodiment is also referred to as a head-up display device. The vehicledisplay device 10 displays a virtual image 110 in front of an eyepoint201 of a vehicle 100. The eyepoint 201 is a predetermined position as aviewpoint position of a driver 200 seated in a driver's seat.

The vehicle display device 10 is disposed inside a dashboard 101 of thevehicle 100. There is an opening 101 a provided on an upper surface ofthe dashboard 101. The vehicle display device 10 projects an image ontoa windshield 102 through the opening 101 a. The windshield 102 is areflector located in front of the eyepoint 201 of the vehicle 100. Thewindshield 102 has translucency, for example, and reflects the lightincident from the vehicle display device 10 toward the eyepoint 201. Thedriver 200 recognizes the image reflected by the windshield 102 as thevirtual image 110. For the driver 200, the virtual image 110 isrecognized as being present ahead of the windshield 102.

The vehicle display device 10 includes a mirror device 1 and an imagedisplay device 11. The image display device 11 is a device that outputsdisplay light, represented by a laser scanner or a liquid crystaldisplay device, for example. The mirror device 1 reflects the displaylight output from the image display device 11 toward the windshield 102.The mirror device 1 of the present embodiment is a movable mirror devicethat can change the direction of the reflecting surface.

As illustrated in FIGS. 2 and 3, the mirror device 1 includes a mirror2, a holding member 3, a motor 4, a worm 5, a rotating member 6, acoupling member 7, a first spring 8, a second spring 9, and a bearingmember 12.

The mirror 2 includes a mirror body 20, a rotation shaft 21, and acoupling shaft 22. The mirror body 20, the rotation shaft 21, and thecoupling shaft 22 are integrally molded with synthetic resin, forexample. The mirror body 20 has a reflecting surface 20 a. Thereflecting surface 20 a is a recessed curved surface and expands thedisplay light output from the image display device 11 to be reflectedtoward the windshield 102. The shape of the reflecting surface 20 a ofthe present embodiment is a freeform surface. The reflecting surface 20a may have a reflective layer formed by vapor deposition or the like.

As illustrated in FIGS. 3 and 4, the rotation shaft 21 has a first shaftportion 21A and a second shaft portion 21B. The first shaft portion 21Aand the second shaft portion 21B are arranged at the position of a firstaxis X1. The first axis X1 is a rotation center of the mirror 2. Thecentral axes of the first shaft portion 21A and the second shaft portion21B are individually located on the first axis X1. The first shaftportion 21A protrudes from a first side surface 20 b of the mirror body20 along the first axis X1. The second shaft portion 21B protrudes froma second side surface 20 c of the mirror body 20 along the first axisX1.

The first shaft portion 21A has a base end portion 21 d and a tip endportion 21 e. The base end portion 21 d is a base end side part of thefirst shaft portion 21A and is connected to the first side surface 20 b.The base end portion 21 d has a columnar shape. The tip end portion 21 eprotrudes from a tip end surface of the base end portion 21 d along thefirst axis X1. The tip end portion 21 e has a flat plate shape having asubstantially rectangular cross section. The tip end portion 21 e has athrough hole to which a screw is inserted. The second shaft portion 21Bhas a columnar shape. As illustrated in FIG. 4, there is a protrusion 21f provided at the tip end of the second shaft portion 21B. Theprotrusion 21 f protrudes in the radial direction.

The coupling shaft 22 is arranged at the position of a second axis X2.The second axis X2 is parallel to the first axis X1 and is separatedfrom the first axis X1. The central axis of the coupling shaft 22 islocated on the second axis X2. The coupling shaft 22 protrudes from thefirst side surface 20 b of the mirror body 20 along the second axis X2.The coupling shaft 22 has a base end portion 22 a and a tip end portion22 b. The base end portion 22 a is a base end-side portion of the secondshaft portion 21B and is connected to the first side surface 20 b. Thebase end portion 22 a has a columnar shape. The tip end portion 22 bprotrudes from a tip end surface of the base end portion 22 a along thesecond axis X2. The tip end portion 22 b has a flat plate shape having asubstantially rectangular cross section. The tip end portion 22 b has athrough hole to which a screw is inserted.

As illustrated in FIG. 5, the holding member 3 has a vertical wall 30,an upper wall 31, a lower wall 32, a locking wall 33, a support portion34, a hook 36, and a tubular portion 37. The holding member 3 isintegrally molded with synthetic resin, for example. The vertical wall30 is a main body of the holding member 3 and is formed in a flat plateshape. The upper wall 31 and the lower wall 32 are provided so as to besubstantially orthogonal to the vertical wall 30. The upper wall 31 andthe lower wall 32 face each other. The holding member 3 is fixed to ahousing of the vehicle display device 10 so that the upper wall 31 andthe lower wall 32 face each other in a vehicle up-down direction, forexample.

The upper wall 31 has a motor holder 31 a that holds the motor 4. Themotor holder 31 a includes a through hole 31 b penetrating the upperwall 31, and a screw hole 31 c. The upper wall 31 supports a housing 40of the motor 4. an output shaft 41 of the motor 4 is inserted into thethrough hole 31 b. The screw for fixing the housing 40 to the upper wall31 is screwed into the screw hole 31 c. The hook 36 is an arm-shapedportion connected to the upper wall 31. One end of the first spring 8 ishooked on the hook 36 and fixed by the hook 36. A tip end portion of thehook 36 is bent so as to be able to lock the first spring 8.

The lower wall 32 has a support hole 32 a. The support hole 32 a may bea recess provided in the lower wall 32 or may be a through holepenetrating the lower wall 32. The support hole 32 a of the presentembodiment penetrates the lower wall 32. The lower wall 32 rotatablysupports the rotating member 6 in the support hole 32 a.

The locking wall 33 protrudes from the vertical wall 30 and extends fromthe upper wall 31 to the lower wall 32. The locking wall 33 is acomponent of a stopper mechanism 16 that restricts the rotation range ofthe worm 5.

The support portion 34 is a portion that supports the first shaftportion 21A of the mirror 2 and is elastically deformable. The supportportion 34 has a function as a slide bearing that slidably supports thefirst shaft portion 21A and a function of aligning the first shaftportion 21A. The support portion 34 has a cylindrical shape andprotrudes from the vertical wall 30 in a direction orthogonal to thevertical wall 30. A tip end 34 b of the support portion 34 is a free endthat is not fixed. The support portion 34 of the present embodimentincludes three pieces 35 (35A, 35B, and 35C). As illustrated in FIG. 6or the like, the pieces 35 are located at equal intervals in acircumferential direction around a central axis C1. There is a slit 34 aprovided between two adjacent pieces 35. That is, the support portion 34has three pieces 35 separated by the slits 34 a. Hereinafter, twodirections orthogonal to the central axis C1 are referred to as a“second direction Y” and a “third direction Z”. The second direction Yand the third direction Z are orthogonal to each other. The seconddirection Y and the third direction Z are, for example, the horizontaldirection and the vertical direction.

There is a tubular portion 37 provided outside the support portion 34.The tubular portion 37 protrudes from the vertical wall 30 and surroundsthe support portion 34. The inner circumferential surface of the tubularportion 37 has a circular cross-sectional shape. The tubular portion 37is arranged coaxially with the support portion 34. The second spring 9is inserted between the tubular portion 37 and the support portion 34.

As illustrated in FIGS. 5 and 7, the slit 34 a extends in the axialdirection of the support portion 34 from the tip end 34 b toward a baseend 34 c of the support portion 34. In the present embodiment, theentire portion of the support portion 34 from the tip end 34 b to thebase end 34 c is divided into three pieces 35. Each of the pieces 35 isconnected to the vertical wall 30 at the base end 34 c, and isindividually supported by the vertical wall 30. That is, each of thepieces 35 is formed as a cantilever whose base end 34 c is a fixed end.The piece 35 has an arcuate cross-sectional shape as illustrated in FIG.6.

As illustrated in FIG. 7, the support portion 34 has a tapered shape.That is, the support portion 34 has the tip end 34 b which is smaller indiameter than the base end 34 c. A radius R1 of the innercircumferential surface of the support portion 34 at the tip end 34 b issmaller than a radius R2 of the inner circumferential surface of thesupport portion 34 at the base end 34 c. That is, the support portion 34has a tapered shape in which the inner diameter (D1=2×R1) at the tip end34 b is smaller than the inner diameter (D2=2×R2) at the base end 34 c.The inner diameter D1 at the tip end 34 b is smaller than the outerdiameter D3 of the base end portion 21 d of the mirror 2.

The first shaft portion 21A of the mirror 2 is inserted into the supportportion 34 from the base end 34 c. At this time, the base end portion 21d is inserted into the support portion 34 while spreading the supportportion 34 outward in the radial direction. In other words, the base endportion 21 d is inserted into the support portion 34 while flexiblydeforming the piece 35 outward in the radial direction.

FIG. 8 illustrates the first shaft portion 21A inserted into the supportportion 34. The support portion 34 supports the base end portion 21 d bythe piece 35. Each of the pieces 35 is formed so as to slidably supportthe base end portion 21 d. For example, the support portion 34 maysupport the base end portion 21 d in a state where a portion on the tipend 34 b side is in contact with the base end portion 21 d and a portionon the base end 34 c side is separated from the base end portion 21 d.By supporting the first shaft portion 21A by the plurality of pieces 35evenly arranged in the circumferential direction, the support portion 34can suppress the displacement of the first shaft portion 21A. Thesupport portion 34 holds the first shaft portion 21A against vibrationsin the second direction Y and the third direction Z so as to restrictmovement of the first shaft portion 21A in the second direction Y whilerestricting the movement of the first shaft portion 21A in the thirddirection Z.

As illustrated in FIG. 9, the bearing member 12 includes a tubularportion 13 and a support portion 14 that is elastically deformable. Thesupport portion 14 has a configuration similar to the support portion 34of the holding member 3. The tubular portion 13 and the support portion14 are integrally molded with synthetic resin, for example. The tubularportion 13 has a cylindrical shape. There are protrusion 13 a and afixing portion 13 b provided on the outer surface of the tubular portion13. The bearing member 12 is fixed to the housing of the vehicle displaydevice 10 at the protrusion 13 a and the fixing portion 13 b.

The support portion 14 is a portion that supports the second shaftportion 21B of the mirror 2. The support portion 14 has a function as aslide bearing that slidably supports the second shaft portion 21B and afunction of aligning the second shaft portion 21B. The support portion14 has a cylindrical shape and is provided coaxially with the tubularportion 13. The support portion 14 has three pieces (15A, 15B, and 15C).The pieces 15 are located inside the tubular portion 13 and are arrangedat equal intervals in the circumferential direction. There is a slit 14a provided between two adjacent pieces 15. That is, the support portion14 has three pieces 15 separated by the slits 14 a.

The slit 14 a extends in the axial direction of the support portion 14from a tip end 14 b toward a base end 14 c of the support portion 14. Inthe present embodiment, the entire portion of the support portion 14from the tip end 14 b to the base end 14 c is divided into three pieces15. Each of the pieces 15 is connected to the tubular portion 13 at thebase end 14 c, and is individually supported by the tubular portion 13.The piece 15 has an arcuate cross-sectional shape. The shape of thesupport portion 14 is a tapered shape, that is, the inner diameter atthe tip end 14 b is smaller than the inner diameter at the base end 14c.

The second shaft portion 21B of the mirror 2 is inserted into thesupport portion 14 from the base end 14 c. At this time, the secondshaft portion 21B is inserted into the support portion 14 whilespreading the support portion 14 outward in the radial direction. Inother words, the second shaft portion 21B is inserted into the supportportion 14 while flexibly deforming the piece 15 outward in the radialdirection.

FIG. 10 illustrates the second shaft portion 21B inserted in the supportportion 14. The support portion 14 supports the second shaft portion 21Bby the three pieces 15. Each of the pieces 15 is formed so as toslidably support the second shaft portion 21B. For example, the supportportion 14 may support the second shaft portion 21B in a state where aportion on the tip end 14 b side is in contact with the second shaftportion 21B and a portion on the base end 14 c side is separated fromthe second shaft portion 21B.

The motor 4 has a housing 40, the output shaft 41, and a collar 42, asillustrated in FIG. 3. The housing 40 is fixed to the upper wall 31 ofthe holding member 3. The motor 4 rotates the output shaft 41 by theelectric power supplied from a battery or the like of the vehicle 100.The tip end portion of the output shaft 41 is formed in a flat plateshape. The output shaft 41 is inserted into the collar 42 and fittedwith the worm 5. The collar 42 rotatably supports the shaft portion ofthe worm 5.

As illustrated in FIG. 11, the worm 5 has a gear body 50, a connectingshaft 51, a support shaft 52, a sliding portion 53, and a worm-sidecontact portion 54. The worm 5 is integrally molded with syntheticresin, for example. The gear body 50 has a substantially cylindricalshape or a columnar shape. The gear body 50 has helical gear teeth 50 a.The connecting shaft 51 is connected to one end of the gear body 50. Thesupport shaft 52 and the sliding portion 53 are connected to the otherend of the gear body 50. The connecting shaft 51 and the support shaft52 are coaxially arranged.

The connecting shaft 51 is a portion connected to the output shaft 41 ofthe motor 4. As illustrated in FIG. 12, the connecting shaft 51 has acylindrical shape. The connecting shaft 51 includes a fitting portion 51a. The fitting portion 51 a clamps the output shaft 41 of the motor 4 soas to connect the worm 5 and the output shaft 41 in such a way toprohibit their relative rotation.

As illustrated in FIGS. 11 and 13, the sliding portion 53 has asubstantially disc shape. The sliding portion 53 has a sliding surface53 a orthogonal to the axial direction. The worm 5 is supported by therotating member 6 on the sliding surface 53 a. The support shaft 52protrudes from the sliding surface 53 a in the axial direction. Thesupport shaft 52 has a substantially columnar shape. The worm-sidecontact portion 54 is a protrusion protruding from the outercircumferential surface of the sliding portion 53. As illustrated inFIG. 13, the worm-side contact portion 54 of the present embodimentprotrudes in the tangential direction from the outer circumferentialsurface of the sliding portion 53. The worm-side contact portion 54 hascontact surfaces 54 a and 54 b that come in contact with the rotatingmember 6.

As illustrated in FIGS. 14 and 15, the rotating member 6 includes a mainbody 60, a support shaft 61, a first contact portion 62, and a secondcontact portion 63. The rotating member 6 is integrally molded withsynthetic resin, for example. The main body 60 has a substantially discshape. The main body 60 has a first sliding surface 60 a and a secondsliding surface 60 b. The first sliding surface 60 a and the secondsliding surface 60 b face opposite to each other. The first slidingsurface 60 a is a surface that supports the sliding portion 53 of theworm 5. The sliding surface 53 a and the first sliding surface 60 aslide, thereby allowing the worm 5 and the rotating member 6 to rotaterelative to each other.

The second sliding surface 60 b is a surface supported by the lower wall32 of the holding member 3. The second sliding surface 60 b and thelower wall 32 slide, thereby allowing the rotating member 6 to rotaterelative to the lower wall 32. The support shaft 61 protrudes from thesecond sliding surface 60 b in the axial direction. The rotating member6 has a through hole 64 penetrating the main body 60 and the supportshaft 61. The through hole 64 is formed coaxially with the central axisof the main body 60 and the support shaft 61. The support shaft 52 ofthe worm 5 is inserted into the through hole 64.

The first contact portion 62 protrudes from the first sliding surface 60a in the axial direction. The first contact portion 62 is provided on anouter edge of the main body 60, for example. A width W1 of the firstcontact portion 62 in the circumferential direction may be the sizesimilar to the diameter of the through hole 64.

The second contact portion 63 protrudes from the outer circumferentialsurface of the main body 60. The direction of protrusion of the secondcontact portion 63 is the radial direction, for example. A width W2 ofthe second contact portion 63 in the circumferential direction may bethe size similar to the diameter of the through hole 64.

As illustrated in FIG. 3, the coupling member 7 has a main body 70 and agear unit 71. The gear unit 71 is fixed to a gear mounting portion 73 ofthe main body 70. As illustrated in FIGS. 16 to 18, the main body 70includes a base 72, a gear mounting portion 73, and a shaft portion 74.The main body 70 is integrally molded with synthetic resin, for example.The main body 70 is preferably formed of a material having a higherrigidity or higher elastic modulus compared to the material of themirror 2. The base 72 has a substantially prismatic shape. The base 72includes a first end 72 a and a second end 72 b. The first end 72 a isone end of the base 72 in the longitudinal direction. The second end 72b is the other end of the base 72 in the longitudinal direction.

The base 72 has a first surface 72 c and a second surface 72 d. Thefirst surface 72 c and the second surface 72 d are side surfaces of thebase 72. The first surface 72 c and the second surface 72 d faceopposite to each other. The coupling member 7 is coupled to the mirror 2in a posture in which the first surface 72 c faces the mirror 2.

The gear mounting portion 73 is connected to the first end 72 a of thebase 72. The gear mounting portion 73 has a substantially rectangularparallelepiped shape. The gear mounting portion 73 has a screw hole 73 aand a protrusion 73 b. The gear unit 71 is positioned by the protrusion73 b. The shaft portion 74 protrudes from the second end 72 b of thebase 72. More specifically, the shaft portion 74 protrudes from thesecond surface 72 d of the base 72 in a direction orthogonal to thesecond surface 72 d. The shaft portion 74 has a substantially columnarshape. The shaft portion 74 has, on its tip end portion, a groove 74 aformed to hold the end of the first spring 8. The groove 74 a is formedover the entire outer circumferential surface of the shaft portion 74.The end of the first spring 8 is coupled to the groove 74 a.

The base 72 includes a first coupling portion 75, a second couplingportion 76, and a boss 77. The first coupling portion 75 is a throughhole formed in the first end 72 a of the base 72. The first couplingportion 75 opens on both the first surface 72 c and the second surface72 d. The first coupling portion 75 has a cross-sectional shape in whichboth ends of a rectangle are curved in an arc shape. The first shaftportion 21A of the mirror 2 is inserted into the first coupling portion75 so as to be coupled to the first coupling portion 75.

The second coupling portion 76 is a recess formed in the second end 72 bof the base 72, as illustrated in FIGS. 17 and 18. The second couplingportion 76 is open on the first surface 72 c and is recessed toward thesecond surface 72 d. The second coupling portion 76 has across-sectional shape in which both ends of a rectangle are curved in anarc shape. The coupling shaft 22 of the mirror 2 is inserted into thesecond coupling portion 76 so as to be coupled to the second couplingportion 76. The shaft portion 74 is arranged coaxially with the secondcoupling portion 76, for example.

The boss 77 is a rib protruding from the first surface 72 c of the base72. The bosses 77 are arranged one on each side of the opening of thefirst coupling portion 75. The boss 77 has an arcuate cross-sectionalshape. The two bosses 77 form a substantially cylindrical boss. The boss77 is inserted into the second spring 9 and holds the second spring 9.

As illustrated in FIG. 19, the gear unit 71 has a base 71 a and aplurality of gear teeth 71 b. The gear unit 71 is integrally molded withsynthetic resin, for example. The base 71 a is formed in a rectangularplate shape. The base 71 a has a recess 71 c corresponding to theprotrusion 73 b of the main body 70 and a through hole 71 dcorresponding to the screw hole 73 a. The screw for fastening the mainbody 70 and the gear unit 71 is inserted into the through hole 71 d andscrewed into the screw hole 73 a of the main body 70. The plurality ofgear teeth 71 b is arranged on one side of the base 71 a. The gear teeth71 b are helical gear teeth and mesh with the gear teeth 50 a of theworm 5.

The first spring 8 illustrated in FIG. 3 or the like includes a springbody 81, a first ring 82, and a second ring 83. The spring body 81 is anexpandable/contractible spring, and an example of this is a coil spring.The first ring 82 is connected to one end of the spring body 81 whilethe second ring 83 is connected to the other end of the spring body 81.The first ring 82 is hooked on a hook 36 of the holding member 3. Thesecond ring 83 is hooked on the shaft portion 74 of the coupling member7. The expansion/contraction direction of the first spring 8 is adirection orthogonal to the axial direction of the rotation shaft 21.

The second spring 9 is an expandable/contractible spring, and an exampleof this is a coil spring. The boss 77 of the coupling member 7 isinserted into one end of the second spring 9. The support portion 34 ofthe holding member 3 is inserted into the other end of the second spring9. The second spring 9 is housed between the holding member 3 and thecoupling member 7 in a contracted state. Therefore, the second spring 9applies a biasing force to the coupling member 7 in the axial directionof the rotation shaft 21. The second spring 9 restricts the movement ofthe coupling member 7 and the mirror 2 in the axial direction, andpositions the coupling member 7 and the mirror 2.

FIGS. 20 and 21 illustrate enlarged views of the vicinity of thecoupling member 7. As illustrated in FIG. 21, the first shaft portion21A of the mirror 2 is rotatably supported by the support portion 34 ofthe holding member 3. Furthermore, the tip end portion 21 e of the firstshaft portion 21A is inserted into the first coupling portion 75 of thecoupling member 7 and coupled to the first coupling portion 75. Thesecond shaft portion 21B of the mirror 2 is inserted into the secondcoupling portion 76 of the coupling member 7 and coupled to the secondcoupling portion 76. Therefore, the coupling member 7 rotates togetherwith the mirror 2. The second spring 9 is interposed between thecoupling member 7 and the holding member 3 and presses the couplingmember 7.

As illustrated in FIG. 20, the gear teeth 71 b of the coupling member 7mesh with the gear teeth 50 a of the worm 5. The first ring 82 of thefirst spring 8 is hooked on the hook 36 of the holding member 3 and isimmovably fixed. The second ring 83 of the first spring 8 is hooked onthe shaft portion 74 of the coupling member 7.

When the motor 4 rotates the worm 5, a driving force F1 in the axialdirection of the worm 5 is applied from the worm 5 to the gear unit 71.The driving force F1 causes the coupling member 7 to pivot about thefirst axis X1 as a rotation center, as illustrated by arrow Y1. Themirror 2 pivots integrally with the coupling member 7. The driving forceF1 is transmitted from the first coupling portion 75 to the first shaftportion 21A while being transmitted from the second coupling portion 76to the coupling shaft 22.

When the coupling member 7 pivots, the movement of the shaft portion 74causes the spring body 81 of the first spring 8 to expand and contract.The first spring 8 is hooked on the shaft portion 74 and the hook 36 inan expanded state. In other words, the first spring 8 is held by thecoupling member 7 and the holding member 3 so that the spring body 81 isconstantly in the expanded state. Therefore, the first spring 8 appliesa spring force F2 in the pulling direction to the shaft portion 74. Thefirst spring 8 uses the spring force F2 to reduce the play caused by thebacklash between the gear unit 71 and the worm 5. The first spring 8 cansuppress the vibration of the mirror 2 and improve the accuracy ofrotational position control for the mirror 2.

As described above, in the mirror device 1 of the present embodiment,the first spring 8 is coupled to the coupling member 7. This cansuppress the deformation of the mirror 2 as described below. As acomparative example, a configuration in which the second ring 83 of thefirst spring 8, instead of the coupling member 7, is coupled to thecoupling shaft 22 will be examined. In this case, the spring force F2generates a stress to bend the mirror 2. For example, action of thespring force F2 on the coupling shaft 22 in a state where the firstshaft portion 21A is constrained would cause a bending stress to act onthe mirror body 20. The mirror device of the comparative example has apossibility of deformation of the mirror 2 due to reduction in therigidity of the mirror 2 caused by the heat or load applied for a longperiod of time.

In the mirror device 1 of the present embodiment, the coupling member 7receives both the driving force F1 and the spring force F2. That is, thecoupling member 7 mainly receives the bending moment caused by thedriving force F1 and the spring force F2. Therefore, force that deformsthe mirror 2 is unlikely to act on the mirror 2. Consequently, themirror device 1 of the present embodiment can suppress the deformationof the mirror 2.

Furthermore, in the mirror device 1 of the present embodiment, therotation shaft 21 is rotatably supported by the tubular support portions34 and 14 as described with reference to FIGS. 8 and 10. The rotationshaft 21 is inserted into the support portions 34 and 14 while spreadingthe support portions 34 and 14, and is slidably supported by the supportportions 34 and 14. The tubular support portions 34 and 14 restrict themovement of the rotation shaft 21 in a direction orthogonal to the axis.Therefore, the mirror device 1 of the present embodiment can suppressthe displacement of the rotation shaft 21 and align the rotation shaft21.

Furthermore, the mirror device 1 of the present embodiment has thestopper mechanism 16 including the rotating member 6. Therefore, asdescribed below, the degree of freedom in controlling the rotation ofthe mirror 2 can be improved. For example, the mirror device 1 of thepresent embodiment is capable of increasing the pivot angle of themirror 2.

FIG. 22 illustrates the stopper mechanism 16 in which the worm 5 and therotating member 6 are in a first stop position. The stopper mechanism 16includes the worm-side contact portion 54 of the worm 5, the rotatingmember 6, and the locking wall 33. Rotation of the rotating member 6 andthe worm 5 in a first rotation direction A1 is restricted at the firststop position. The first rotation direction A1 is for rotation in adirection of bringing the gear unit 71 of the coupling member 7 closerto the motor 4, for example. The first rotation direction A1 is arotation direction that increases an inclination angle of the mirror 2,for example. A second rotation direction A2 is a rotation directionopposite to the first rotation direction A1. The second rotationdirection A2 is for rotation in a direction of bringing the gear unit 71of the coupling member 7 away from the motor 4, for example. The secondrotation direction A2 is a rotation direction that decreases theinclination angle of the mirror 2, for example.

As illustrated in FIG. 22, the second contact portion 63 of the rotatingmember 6 is locked by the locking wall 33 of the holding member 3. Morespecifically, the second contact portion 63 is locked by an inner wallsurface 33 a of the locking wall 33. The inner wall surface 33 arestricts rotation of the rotating member 6 in the first rotationdirection A1. In contrast, the rotating member 6 is allowed to rotate inthe second rotation direction A2. The worm-side contact portion 54 ofthe worm 5 is locked by the first contact portion 62 of the rotatingmember 6. The first contact portion 62 restricts rotation of the worm 5in the first rotation direction A1. In contrast, the worm 5 is allowedto rotate in the second rotation direction A2.

When the motor 4 applies a rotational force in the second rotationdirection A2 to the worm 5 from the state illustrated in FIG. 22, theworm 5 rotates as illustrated by arrow Y2 in FIG. 23. At this time, therotating member 6 may remain stopped or may be rotated by the worm 5.Here, the operation when the rotating member 6 is stopped and the worm 5rotates relative to the rotating member 6 will be described.

When the worm 5 rotates relative to the rotating member 6 by a firstangle θ1 from the position illustrated in FIG. 22, the worm-side contactportion 54 comes in contact with the first contact portion 62 asillustrated in FIG. 24. The first angle θ1 in the present embodiment isapproximately 270°. The first angle θ1 is an angle determined inaccordance with the width W1 of the first contact portion 62, the shapeof the worm-side contact portion 54, or the like. The first contactportion 62 and the worm-side contact portion 54 of the presentembodiment are configured to enable the worm 5 to rotate approximately270° relative to the rotating member 6. The first angle θ1 can be setaccording to the target value of the pivoting range of the mirror 2 orthe like. The first contact portion 62 and the worm-side contact portion54 are preferably configured to enable the worm 5 to rotate relative tothe rotating member 6 by more than half a rotation.

When the worm-side contact portion 54 comes in contact with the firstcontact portion 62, the rotational force in the second rotationdirection A2 output from the motor 4 is transmitted from the worm-sidecontact portion 54 to the rotating member 6. Therefore, in a case wherethe worm 5 further rotates in the second rotation direction A2, therotating member 6 rotates together with the worm 5.

When the rotating member 6 rotates relative to the lower wall 32 by asecond angle θ2 from the position illustrated in FIG. 24, the secondcontact portion 63 comes in contact with the locking wall 33 asillustrated in FIG. 25. The second contact portion 63 comes in contactwith an end surface 33 b of the locking wall 33 and is locked by the endsurface 33 b. The end surface 33 b locks the second contact portion 63to stop the rotation of the rotating member 6 and the worm 5. That is,rotation of the rotating member 6 and the worm 5 in a second rotationdirection A2 is restricted at the second stop position.

The second angle θ2 of the present embodiment is approximately 320°. Thesecond angle θ2 is an angle determined according to the width W2 of thesecond contact portion 63, the shape of the locking wall 33, or thelike. The second contact portion 63 and the locking wall 33 of thepresent embodiment are configured to allow the rotating member 6 torotate relative to the holding member 3 by approximately 320°. Thesecond angle θ2 can be set according to the target value of the pivotingrange of the mirror 2 or the like. The second contact portion 63 and thelocking wall 33 are preferably configured to enable the rotating member6 to rotate relative to the holding member 3 by more than half arotation.

The position of the worm 5 and the rotating member 6 illustrated in FIG.25 is referred to as the second stop position. The second stop positionis a position where rotation of the worm 5 and the rotating member 6 inthe second rotation direction A2 is restricted by the locking wall 33.

In this manner, in the mirror device 1 of the present embodiment, theworm 5 can rotate approximately 590° between the first stop position andthe second stop position. That is, the worm 5 can rotate relative to theholding member 3 by more than 1.5 rotations (540°). In this manner, thestopper mechanism 16 of the present embodiment allows the worm 5 torotate by more than one rotation (360°). As a comparative example, astructure in which the rotating member 6 is not provided and theworm-side contact portion 54 of the worm 5 is locked by the locking wall33 will be examined. In the comparative example, the worm 5 can rotateonly within a range of less than one rotation. In contrast, the rotationrange of the worm 5 greatly exceeds one rotation in the mirror device 1of the embodiment.

According to the mirror device 1 of the present embodiment, the degreeof freedom in controlling the rotation of the mirror 2 is improved. Forexample, the pivoting range of the mirror 2 can be set to a large range.Furthermore, in the mirror device 1 of the embodiment, the reductionratio or the increasing ratio from the motor 4 to the rotation shaft 21can be selected from a wide range. Increasing the pivoting range of themirror 2 also increases the expansion/contraction amount of the firstspring 8, which is likely to increase the maximum value of the springforce F2 as a result. Here, the mirror device 1 of the presentembodiment has a configuration in which the coupling member 7 receivesthe spring force F2. Therefore, the mirror 2 is unlikely to be deformedeven with the increased spring force F2.

As described above, the mirror device 1 of the present embodimentincludes the mirror 2, the gear unit 71, the worm 5, the holding member3, the motor 4, and the stopper mechanism 16. The mirror 2 includes therotation shaft 21 that is pivotably supported and the reflecting surface20 a that reflects display light. The gear unit 71 includes gear teeth71 b and is coupled to the rotation shaft 21. The worm 5 has the helicalgear teeth 50 a meshing with the gear teeth 71 b. The holding member 3rotatably supports the worm 5. The motor 4 is held by the holding member3 and is connected to the worm 5. The motor 4 rotationally drives therotation shaft 21 via the worm 5 and the gear teeth 71 b.

The stopper mechanism 16 includes the rotating member 6 arrangedcoaxially with the worm 5 and restricts the rotation range of the worm5. The rotating member 6 can rotate relative to the holding member 3 andthe worm 5, individually. The stopper mechanism 16 includes the firstcontact portion 62 and the second contact portion 63 provided on therotating member 6. The first contact portion 62 comes in contact withthe worm 5 and receives force in the rotation direction from the worm 5.The second contact portion 63 is locked by the holding member 3. Thestopper mechanism 16 is configured to allow the worm 5 to rotaterelative to the holding member 3 by more than one rotation. The mirrordevice 1 according to the present embodiment is capable of increasingthe degree of freedom in controlling the rotational position of themirror 2 by widening the rotation range of the worm 5. Furthermore,according to the mirror device 1 of the present embodiment, it ispossible to achieve a mechanism to expand the rotation range of the worm5 with a reduced space.

The stopper mechanism 16 of the present embodiment has the worm-sidecontact portion 54 and the locking wall 33. The worm-side contactportion 54 is provided on the worm 5, and comes in contact with thefirst contact portion 62 to rotate the rotating member 6 together withthe worm 5. The locking wall 33 is an example of a stopper portionprovided on the holding member 3, and comes in contact with the secondcontact portion 63 to restrict the rotation of the rotating member 6 andthe worm 5.

The first contact portion 62 and the worm-side contact portion 54 arepreferably configured to enable the worm 5 to rotate relative to therotating member 6 by more than half a rotation. The second contactportion 63 and the locking wall 33 are preferably configured to enablethe rotating member 6 to rotate relative to the holding member 3 by morethan half a rotation. The stopper mechanism 16 is preferably configuredto enable the worm 5 to rotate relative to the holding member 3 by morethan 1.5 rotations.

The rotating member 6 of the present embodiment has a disc-shaped mainbody 60 rotatably supported by the holding member 3. The first contactportion 62 protrudes from the outer edge of the main body 60 in theaxial direction. The second contact portion 63 protrudes outward in theradial direction from the outer circumferential surface of the main body60. Since the first contact portion 62 and the second contact portion 63protrude from different surfaces of the main body 60, it is possible tomaximize the rotation range of the worm 5.

Modification of Embodiment

The arrangement and shape of the rotating member 6 are not limited tothe arrangement and shape exemplified in the above embodiment. Thestopper mechanism 16 may have a plurality of rotating members 6. Forexample, the stopper mechanism 16 may have a first rotating member and asecond rotating member. In this case, the first rotating member isarranged on the worm 5 side, and the second rotating member is arrangedon the holding member 3 side. The worm 5 rotates the first rotatingmember and thereafter rotates the second rotating member. The secondrotating member is locked by the stopper portion of the holding member3, thereby restricting the rotation of the first rotating member, thesecond rotating member, and the worm 5.

The contents disclosed in the above embodiments and modification can beexecuted in appropriate combination with each other.

The mirror device according to the present embodiment has a stoppermechanism including a rotating member. The stopper mechanism includes: afirst contact portion that is provided on the rotating member and comesin contact with the worm to receive force in the rotation direction fromthe worm; and a second contact portion that is provided on the rotatingmember and is locked by the holding member, and allows the worm torotate relative to the holding member by more than one rotation. Themirror device according to the present embodiment is capable ofachieving an effect of increasing the degree of freedom in controllingthe rotational position of the mirror by widening the rotation range ofthe worm.

Although the invention has been described with respect to specificembodiments for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

What is claimed is:
 1. A mirror device comprising: a mirror including arotation shaft pivotably supported and a reflecting surface thatreflects display light; a gear unit having gear teeth and coupled to therotation shaft; a worm that meshes with the gear teeth; a holding memberthat rotatably supports the worm; a motor that is held by the holdingmember, connected to the worm, and configured to rotationally drive therotation shaft via the worm and the gear teeth; and a stopper mechanismthat has a rotating member disposed coaxially with the worm, andrestricts a rotation range of the worm, wherein the rotating member isrotatable relative to the holding member and the worm individually, thestopper mechanism includes: a first contact portion that is provided onthe rotating member and comes in contact with the worm to receive forcein the rotation direction from the worm; and a second contact portionthat is provided on the rotating member and is locked by the holdingmember, and the stopper mechanism is configured to allow the worm torotate relative to the holding member by more than one rotation.
 2. Themirror device according to claim 1, wherein the stopper mechanismincludes: a worm-side contact portion that is provided on the worm andthat comes in contact with the first contact portion to rotate therotating member together with the worm; and a stopper portion that isprovided on the holding member and that comes in contact with the secondcontact portion to restrict the rotation of the rotating member and theworm.
 3. The mirror device according to claim 2, wherein the firstcontact portion and the worm-side contact portion are configured toenable the worm to rotate relative to the rotating member by more thanhalf a rotation.
 4. The mirror device according to claim 2, wherein thesecond contact portion and the stopper portion are configured to enablethe rotating member to rotate relative to the holding member by morethan half a rotation.
 5. The mirror device according to claim 3, whereinthe second contact portion and the stopper portion are configured toenable the rotating member to rotate relative to the holding member bymore than half a rotation.
 6. The mirror device according to claim 1,wherein the stopper mechanism is configured to enable the worm to rotaterelative to the holding member by more than 1.5 rotations.
 7. The mirrordevice according to claim 2, wherein the stopper mechanism is configuredto enable the worm to rotate relative to the holding member by more than1.5 rotations.
 8. The mirror device according to claim 3, wherein thestopper mechanism is configured to enable the worm to rotate relative tothe holding member by more than 1.5 rotations.
 9. The mirror deviceaccording to claim 4, wherein the stopper mechanism is configured toenable the worm to rotate relative to the holding member by more than1.5 rotations.
 10. The mirror device according to claim 1, wherein therotating member includes a disc-shaped main body rotatably supported bythe holding member, the first contact portion protrudes from an outeredge of the main body in the axial direction, and the second contactportion protrudes from an outer circumferential surface of the main bodyoutward in the radial direction.
 11. The mirror device according toclaim 2, wherein the rotating member includes a disc-shaped main bodyrotatably supported by the holding member, the first contact portionprotrudes from an outer edge of the main body in the axial direction,and the second contact portion protrudes from an outer circumferentialsurface of the main body outward in the radial direction.
 12. The mirrordevice according to claim 3, wherein the rotating member includes adisc-shaped main body rotatably supported by the holding member, thefirst contact portion protrudes from an outer edge of the main body inthe axial direction, and the second contact portion protrudes from anouter circumferential surface of the main body outward in the radialdirection.
 13. The mirror device according to claim 4, wherein therotating member includes a disc-shaped main body rotatably supported bythe holding member, the first contact portion protrudes from an outeredge of the main body in the axial direction, and the second contactportion protrudes from an outer circumferential surface of the main bodyoutward in the radial direction.
 14. The mirror device according toclaim 6, wherein the rotating member includes a disc-shaped main bodyrotatably supported by the holding member, the first contact portionprotrudes from an outer edge of the main body in the axial direction,and the second contact portion protrudes from an outer circumferentialsurface of the main body outward in the radial direction.
 15. A mirrordevice comprising: a mirror including a rotation shaft pivotablysupported and a reflecting surface that reflects display light; a gearunit having gear teeth and coupled to the rotation shaft; a worm thatmeshes with the gear teeth; a holding member that rotatably supports theworm; a motor that is held by the holding member, connected to the worm,and configured to rotationally drive the rotation shaft via the worm andthe gear teeth; and a stopper mechanism that has a rotating memberdisposed coaxially with the worm, and restricts a rotation range of theworm, wherein the rotating member is rotatable relative to the holdingmember and the worm individually, the stopper mechanism includes: aworm-side contact portion provided on the worm; a first contact portionand a second contact portion that are provided on the rotating member;and a stopper portion provided on the holding member, the worm-sidecontact portion comes in contact with the first contact portion torotate the rotating member together with the worm, the stopper portioncomes in contact with the second contact portion to restrict therotation of the rotating member and the worm, the first contact portionand the worm-side contact portion are configured to enable the worm torotate relative to the rotating member by more than half a rotation, andthe second contact portion and the stopper portion are configured toenable the rotating member to rotate relative to the holding member bymore than half a rotation.